Abstract
OBJECTIVES: This study sought to determine the rate of chemotherapy-related cardiotoxicity and to estimate adherence to recommendations for cardiac monitoring among breast cancer patients treated with chemotherapy. BACKGROUND: Heart failure (HF) is a known complication associated with cancer therapies. Little is known regarding the rate of chemotherapy-related cardiotoxicity and adherence to recommendations for cardiac monitoring among chemotherapy-treated breast cancer patients. METHODS: Patients >18 years of age with a diagnosis of nonmetastatic invasive breast cancer between 2009 and 2014, treated with chemotherapy within 6 months of their diagnosis, were identified in the Truven Health MarketScan (IBM Watson Health, Cambridge, Massachusetts) database. HF, comorbidities, and treatment details were identified using diagnosis and billing codes. Analyses included descriptive statistics, Cox proportional hazard regression, and logistic regression. RESULTS: A total of 16,456 patients were included; the median age was 56 years old. Cardiotoxicity was identified in 4.2% of patients. Therapy with trastuzumab (hazard ratio [HR]: 2.01; 95% confidence interval [CI]: 1.72 to 2.36) and anthracyclines (HR: 1.53; 95% CI: 1.30 to 1.80), Deyo comorbidity scores (HR: 1.38; 95% CI: 1.15 to 1.66; HR: 2.47; 95% CI: 1.94 to 3.15 for scores of 1 and ≥2, respectively), hypertension (HR: 1.28, 95% CI: 1.09 to 1.51), and valve disease (HR: 1.93; 95% CI: 1.48 to 2.51) were associated with an increased risk of cardiotoxicity. Patients ≤35 years of age (HR: 0.37; 95% CI: 0.19 to 0.72) and 36 to 49 years of age (HR: 0.49; 95% CI: 0.38 to 0.62) were less likely to have cardiotoxicity than patients 65 years of age and older. Among 4,325 patients treated with trastuzumab, guideline-adherent cardiac monitoring was identified in 46.2% of patients. Therapies using anthracyclines (odds ratio [OR]: 1.58; 95% CI: 1.35 to 1.87), taxanes (OR: 1.63; 95% CI: 1.27 to 2.08), and radiation (OR: 1.22; 95% CI: 1.08 to 1.39) were associated with guideline-adherent monitoring. CONCLUSIONS: HF is an uncommon complication of breast cancer therapies. The risk was higher among patients treated with trastuzumab or anthracyclines and lower in younger patients. Cardiac monitoring among trastuzumab-treated patients should be a priority among high-risk patients and in the presence of comorbidities or other chemotherapies such as those using anthracyclines.